Game story: 49ers offense vanishes in second half of 32-17 loss to Lions

At least the 49ers’ 11th loss this season offered a different twist. Australian rookie Jarryd Hayne made a surprise start and ran well with the newly acquired DuJuan Harris in Sunday’s 32-17 defeat to the Detroit Lions.

Check that, they ran well in the first half. After halftime, the 49ers offense vanished, getting shut out and reverting to the form that’s doomed them all season.

The 49ers (4-11) thus matched their combined number of regular-season losses from the 2011-2013 seasons, in which they reached the NFC Championship Game each year.

“We’ve been starting slow and finishing strong, and it was the complete opposite today,” quarterback Blaine Gabbert said.

After totaling 265 yards and 17 points in an arguably their best first half this year, Gabbert couldn’t keep pace with Lions quarterback Matthew Stafford, and the 49ers penalty-prone defense didn’t help matters.

Just as mysterious was the 49ers’ disappearing rushing attack. In the first half, Hayne and Harris flourished behind a revamped offensive line, totaling 122 yards on 20 carries. After halftime, the 49ers had just three carries for minus-1 yard against the Lions (6-9).

How flustered was Tomsula? When asked about the Lions defensive adjustments, he said: “I don’t know that they were a step ahead. Obviously they were a step ahead on me. We weren’t getting things done the way we needed to.”

As a result, they’re saddled with their most losses since 2007, and a defeat in next Sunday’s season finale against the St. Louis Rams would give the 49ers their first 4-12 record since 2005. The 49ers already matched a 2005 mark by going 1-7 on the road, which they last did in 2010.

Hayne, a day after getting called up from the practice squad, totaled a pedestrian 27 rushing yards (all in the first half) and five catches in the fourth quarter for 20 yards. Harris, five days after being signed, racked up 74 rushing yards in the first half and barely got into the second half (two carries, minus-1 yard).

Hayne was “happy” with the experience he gained in his first career start, prompted not so much by his diligent work on the scout team the past two months but rather the 49ers’ amazing attrition at running back. Shaun Draugh was out with a knee injury, having started the past six games in place of the injured Carlos Hyde and Reggie Bush.

“I thought he represented himself well,” Tomsula said of Hayne.

Hayne, a former rugby-league star, drew criticism from Tomsula for getting stopped a yard short of a first down on a fourth-and-3 reception. “He’s just got to get to the (first-down) sticks, man,” Tomsula said.

The 49ers trailed 29-17 at that point with 6:50 remaining, so it wasn’t as if that play keyed their defeat. Gabbert’s take on Hayne’s 2-yard catch: “It was going to be a bang-bang play. It’s a game of inches and we fell short.”

Hayne came away confident he belongs in the NFL, and the 49ers indeed plan on keeping him on the roster through the season finale, thus retaining his rights for next season.

“I’m capable of playing at this level,” Hayne said. “Confidence in my own ability is something I have a lot of, and to be able to go out there and perform the way I did today, it shows.

Hayne said he found out in warm-ups that he would start, and what an entrance he and the 49ers made on the game’s first series. They drove 80 yards in 11 plays, culminating with a 1-yard touchdown pass from Gabbert to Vance McDonald, for the 49ers’ first offensive touchdown in the first quarter this year.

The 49ers scored two touchdowns before halftime for only the second time this season, with Torrey Smith’s 16-yard scoring catch putting the 49ers ahead 14-10 in the second quarter.

“It was really a great first half, a great first drive,” left tackle Joe Staley said. “We got in a great tempo, we were able to run the ball with success.”

And then?

“In the second half, we had limited possessions,” Staley said.

Indeed, the 49ers managed only one first down on each of their four series after halftime, turning the ball over on downs twice and punting it twice.

This was Detroit’s fifth win in seven games after a 1-7 start. The Lions had lost their past nine meetings with the 49ers, including a 2011 thriller here that resulted in a postgame, handshake confrontation between then-coaches Jim Harbaugh and Jim Schwartz.

Tomsula, Harbaugh’s maligned successor, was gracious in defeat, stating: “Hats off to Detroit. They did a nice job in the second half and (it) allowed them to win the football game.”